david p



(No Model.)-

p. P. DAVIS.

, PIsTON VALVE AND OHEST. No. 306,138. v Patented O t. 7, 1884.

UNITED STATES PATENT ()rrrcn.

DAVID P. DAVIS, OF JERSEY CITY, NEWV JERSEY, ASSIGNOR TO THE NEIV YORKSAFETY STEAM POlVER COMPANY, OF NEW YORK, N. Y.

PISTON VALVE AND CHEST.

SPECIFICATION forming part of Letters Patent No. 306,l38, dated October7, 1884.

Application filed April 21, 1884. (No model.)

To all whom it may concern Be it known that I, DAVID I. DAVIS, of JerseyCity, in the county of Hudson and State of New Jersey, have invented anImprovement in Piston-Valves and Valve-Chests for Steam- Engines, ofwhich the following is a specification.

Piston valves have heretofore been used quite extensively insteamengines; but the IO rush of the steam in passing through theordinary port from the cylinder during the exhaust causes more or lessunequal pressures on the valve, which results in unequal wear upon thevalve and the valve-seats in the chest.

My improvement relates to steam-ports with deflectors applied therein insuch a manner,

that the steam passes in or out at the two opposite sides of thepiston-valve, thereby equalizing the action of the steam, and preventingthe valve wearing unduly or cutting into its seat. I also providesight-holes with plugs by which to observe the valves, and to facilitatethe adjustment.

In the drawings, Figure l is a longitudinal 2 5 section of the cylinderand valve. Fig. 2 is a cross-section at 00:11, and Fig. 3 is a plan ofthe face of the cylinder.

The cylinder A, piston B, piston-rod 0, packing-gland D, and head E areof any usual or desired character. The valve-chest G is a casting, theunder side or face of which rests upon the face of the cylinder, and isattached thereto by bolts 3, the surfaces being finished off true andscraped to a steam-tight fit. This valve- 3 5 chest can be removed andanother substituted with facility if the valve or its seat becomeinjured. In the middle of the valve-chest there is a cylindrical openingfor the pistonvalve, such valve being composed of the stem 0 h, the twopiston-valves t and k, and the guiderings Z on upon arms extending outfrom the tubular body a, that connects the valves together. Theseguide-rings are for the purpose of enlarging the bearing-surfaces,andenabling the valves to pass the ports freely and lessen wear upon thesurfaces of the valves. These guide-rings are so proportioned as not toobstruct the free exhaust of the steam. The steam is supplied by thepipe 0, and passes into the chamber 0, where it nearly surrounds theinterior cylindrical case in which the valves move, and it is admittedto the cylinder at the ends 0*, and the exhaust-pipe 1) opens into thecentral chamber, 1); or this action may be reversed, and the steamadmitted at p and exhaust take place at 0, the valves being modi fied tosuit, and the eccentric properly placed. The arched partition qseparates the chambers 0 and p, and the cylindrical part of the chest inwhich are the piston-valves is made within this arched partition. Theports 4 and 5, that pass from the respective ends of the cylinder to thevalve-chest are of the ordinary character, except that there aredeflectors or bridges at 6 6, which separate the ports at and 5 into 6 5two parts, and there are bridges or deflectors 7 7 above the bridges 6,such deflectors 7 being part of the steam-chest. The valveports 9 and 10are in the chest, and they are over the deflectors 6 and 7, and theseports allow the steam to pass in or the exhaust to pass off all aroundthe edges of the valves 2' or 7; as the same open or close, in themanner usual with piston-valves; but in consequence of the deflectors 6and 7 the rush of steam is not directly to or from the cylinder,impinging principally in one direction upon the valve, but,

on the contrary, such rush of steam is directed by the deflectors, and,being principally at opposite sides and in opposite directions, is Soequalized to aconsiderable extent on the valve, and hence the wear isless and more uniform, andless power is consum ed in moving thevalve.

I introduce holes through the top of the steamchest, opening into theports 9 and 10, and fit plugs t into the same, so that when these plugsare removed the valves can be observed. This greatly increases thefacility for setting the valves and adjusting the eccentrics to give theproper lead.

I, am aware that pistonvalves have been made with close valve-movingpistons upon the valve-stem outside the valves. In my case theguide-rings for the piston-valves are necessarily placed between thepiston-valves, and they are open to allow the steam to pass freely.

I am also aware that the ports around the piston-valves and within thesteam-chest have been made with bridges at intervals that support thepacking-rings. In my improvement the ports are entirely open around thevalves, and the one deflector in each port simply diverts the steam fromthe valve, causing it to pass at each side of the valve and be balancedin its action.

I claim as my invention 1. The combination, with the steam-cylinder andpiston-valves, of a steam-chest having continuous openings around thevalve, forming ports connecting with the ports in the steamcylinder, anda deflector within each port between the cylinder and the piston-valve,to divert the steam from the valve, substantially as and for the purposeset forth.

2. The combination, with the piston-valves, of the steam-chest havingports 9 and 10, and openings through the valvechest in line with

